Visceral leishmaniasis (VL) is a severe disease with high mortality in both developed and developing countries. The causative agents are the parasites Leishmania chagasi, donovani and infantum depending on geographic location. In Mediterranean countries, co-infection with HIV has become problematic and asymptomatic individuals have been shown to transmit the parasite through transfusion, in both France and Brazil. The tests available for early diagnosis have benefitted by the advent of the recombinant K39 antigen. However, this antigen, while highly specific for active disease, does not adequately detect asymptomatic infections. The studies proposed in this grant take advantage of the recombinant gene B identified from L. chagasi. This will be used as an adjunct to the recombinant K39 in the development of a rapid inexpensive test for the diagnosis of symptomatic and asymptomatic infection. These studies will exploit the expertise of InBios to develop rapid testing in combination with Corixa's K39 and LcGeneB antigens. The studies will also benefit from a close collaboration with renowned consultants domestically and in developing countnes and by access to their serum banks. PROPOSED COMMERCIAL APPLICATION: The proposed studies will lead to the commercialization of diagnostic tests that will aid in the early diagnosis of active and asymptomatic infections with the parasites L .donovani, chagasi and infanturn. The worldwide market for such a test is estimated to be in excess of $10-15 million dollars based on a cost of $1.50 per test.